Although the widespread use of motor cars and motorcycles has brought about much convenience, there are problems associated with their use. For example, if the driver, after parking the car, forgets to switch off all the electrical appliances of the car, e.g. lighting devices in the car or parking lights on the car, such electrical appliances will consume electricity from the battery. When, after a period of time, the driver wishes to activate the engine, he/she may find that the battery in the car cannot provide sufficient electricity to activate the engine. If such a situation often occurs, servicing of the battery may be required, or the battery may even have to be replaced, thus bringing inconvenience and additional outgoings, in terms of both time and money, to the driver or owner of the car.
In the hope of solving the above problem, the following battery low-voltage protectors have been proposed. U.S. Pat. No. 5,200,877 entitled “Battery Protection System” discloses a set of electrical switches and a control process. In use, a system according to this patent will, after a pre-defined period of time and irrespective of whether the drop in voltage of the battery is quick or slow, check whether the battery voltage is below a pre-determined level. If the battery voltage is below the pre-determined level, the system will then cut off the electrical connection between the battery and the load, i.e. electrical appliances, starter and various electricity-consuming devices of the car. However, if, before the expiration of the pre-defined period of time, there has been a large output of electricity, the battery may well be exhausted, thus defeating the purpose of the protection system. In addition, in a system according to this patent, when the battery is cut off from the load, the electrical switches are still connected with the battery, which means that the battery is still in an electricity-discharging state. There is thus still the possibility of exhausting the electricity supply of the battery, preventing activation of the engine.
U.S. Pat. No. 6,424,511 entitled “Automotive Battery Disconnect Device” discloses a design, principle and control devices for electrical switches, in which, again, there is still the problem that when the battery is electrically cut off from the load, the positive terminal of the battery is not totally cut off, and thus still in an electricity-discharging state.
U.S. Pat. No. 4,493,001 entitled “Motor Vehicle Battery Rundown Protection System” discloses a circuit design and principle of a set of electrical switches and controller, in which, similarly, there remains the problem that when the battery is electrically cut off from the load, the positive terminal of the battery is not totally cut off, and thus still in an electricity-discharging state. In addition, a system according to this patent is not easy to install.
The system disclosed in U.S. Pat. No. 5,272,380 entitled “Electrical Supply Control System for a Motor Vehicle” is, again, not easy to install and suffers from the problem that the battery is still connected with electricity-consuming appliances even when the battery is disconnected from the load.
The device disclosed in U.S. Pat. No. 5,315,228 entitled “Battery Charge Monitor and Fuel Gauge” cannot differentiate between a quick and a slow fall in the battery voltage, and thus cannot overcome the problem of not being able to normally activate the engine.
Furthermore, the above proposals do not provide any testing device allowing the user/driver to test whether the relevant devices are in normal working conditions, or any display device informing the user/driver of the current working condition of the devices.
It is thus an object of the present invention to provide a low-voltage protecting device in which the aforesaid shortcomings are mitigated, or at least to provide a useful alternative to the public.
A further object of the present invention is to provide a battery low-voltage protecting device which can totally disconnect the electrical connection between the battery and all electricity-consuming appliances of the car, thus maintaining the voltage level of the battery. Such a device is easy to install and can determine whether to effect such a disconnection, depending on the rate of fall of the voltage level of the battery.
A yet further object of the present invention is to provide a battery low-voltage protecting device which, after installation, allows tests to be conducted, and includes display device indicating whether such is in normal working conditions.